what is jquery

JavaScript
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
jQuery is a lightweight, "write less, do more", JavaScript library.

The purpose of jQuery is to make it  much easier to use JavaScript on
your website. 

jQuery takes a lot of common tasks that require many lines of JavaScript code
to accomplish, and wraps them into methods that you can call with a single
line of code.jQuery is a JavaScript library designed to simplify HTML DOM tree
traversal and manipulation, as well as event handling, CSS animation,
and Ajax.

It is free, open-source software using the permissive MIT License.

As of May 2019, jQuery is used by 73% of the 10 million most popular
websitesnpm install jquery
jQuery is a fast, small, and feature-rich JavaScript library.
It makes things like HTML document traversal and manipulation,
event handling, animation, and Ajax much simpler with an easy-to-use
API that works across a multitude of browsers.

With a combination of versatility and extensibility,
jQuery has changed the way that millions of people write JavaScript.
Source

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